The role of hot‐melt adhesives in sift‐proof sealing

High speed cartoning offers a convenient way to pack a wide range of products. Sift‐proof sealing is a technique which can provide major savings in energy and raw materials, thus reducing both cost and demands on resources. PVA has been the traditional adhesive used, but hot‐melt adhesives have a number of advantages, not least of which is speed. This is becoming increasingly important as packers demand greater production speeds and so hot‐melt adhesives are gradually supplanting PVA. Both elements of the process, adhesive and application equipment, will have to be skilfully engineered in order to cope with the added stresses placed on them by these high speeds. An exciting new development of the sift‐proof technique has recently been unveiled, whereby a treated paper membrane is bonded to the inside of the carton at each end. Not only does this provide a means of applying a complete “circuit” of hot melt to give a totally air‐tight pack but its barrier properties allow the carton to be used for perishable products. Further developments of the sift‐proof technique in the future can be expected.